Highlights of STAR Mid-Term Upgrades

STAR Upgrade Concepts The RHIC facility – Evolution and future Equation of state and the QCD phase diagram 1. Dynamical considerations A. Evidence for Thermalization B. Thermalization Timescale C. Thermalization Mechanisms D. Viscosity 2. Equation of State A. Measurements of Energy Density B. Initial Temperature: How to measure it? 3. Exploring the QCD Phase Diagram A. Search for the QCD critical point B. Medium effects on properties of hadrons 4. Deconfinement 5. Hadronization Gluon Saturation Exploring the spin structure of the nucleon at RHIC-II Summary of the RHIC II Science Working Groups STAR upgrade concepts 1.Preserve large acceptance 2.Extend forward coverage 3.Particle Identification 4.Precise Secondary Vertex 5.Leptons/photons 6.Faster DAQ 7.Cost-effective, do it best

Upgrades to keep the discoveries rolling … Forward Meson Spectrometer –Gluon density distributions, saturation effects, and transverse spin DAQ1000 Upgrade –order of magnitude increase in rate (1KHz) –extra livetime opens the door to rare physics Full Barrel MRPC TOF –extended hadron identification at intermediate p T –Lepton identification at low momentum Heavy Flavor Tracker –high precision Heavy Flavor Tracker near the vertex –opens the door to direct topological ID of Charm & Beauty Forward GEM Tracker –end cap tracker for W sign determination Muon Telescope (BNL LDRD) Forward Reaction Plane Detector A Crystal Calorimeter for low E photons  -  HBT Underway R&D/Proposal Stage Concept Dev.

DAQ1000 Concept Zero suppression done at RB in the DAQ room  Full ~460, bit words transferred over each fiber.  10ms readout time every event. 100hz max rate. No event buffering on FEE  TPC dead during digitization & readout time.  1% dead / hz readout. Zero suppression done at FEE in the Altro  Event transfer times smaller  Combined with slightly faster link, will allow rates ~ hz Event Buffering on FEE  TPC stays alive as long as throughput is < max  Deadtime only caused by TPC Drift..  0.004% dead / hz readout Existing TPCDAQ 1000

TPC FEE and DAQ Upgrade – DAQ 1000 blue pen PASAsALTROs brown ruler FPGAs Fiber Out via SIU FEE In Faster, smaller, better … ( 10x ) Current TPC FEE and DAQ limited to 100 Hz 1 kHz central 3 kHz minBias 5 kHz future Replace TPC FEE with next generation CERN ALTRO, PASA Make the FEE smaller and creates less heat No dead time (well, almost …) More efficient for rare physics probes

MRPC Time-of-Flight collaboration between the United States (DOE) and China (NNSFC, MoST, MoE) in high-energy particle physics detector research State-of-art Multi-gap Resistive Plate Chamber: 6 gap, 3x6cm 2 pad; 23,000 channels, -0.9<  <0.9, 0<  <2 , r=220cm

Physics with TOF Generic detector for PID (hadron and lepton) at mid-rapidity Identified proton/pion at high pT Jet-related spectra and correlation Fluctuation K/ , p/  (Critical point) Resonances ( , ,J/  ) hadronic and dilepton decay channels Open Charm (daughter PID) Leading hadrons Medium Jet dissipates energy PRL95(2005) GeV Au+Au: STAR, PRC72(2006) central peripheral 0.15 < p t < 2 GeV/c real – mixed =1-2=1-2 =1-2=1-2 PRL97(2006)152301

STAR Forward Meson Spectrometer (FMS) Detectors are stacked on the west platform in two movable halves. This view is of the south FMS half, as seen through the retracted west poletip. Schematic of the FMS as seen from the interaction point. The small-cell inner calorimeter has 476 detectors and the large cell outer calorimeter has 788 detectors.

FMS Highlighted Objectives [hep-ex/ ] d(p)+Au     +X gold nuclei 0.001< x <0.1 1.A d(p)+Au     +X measurement of the parton model gluon density distributions xg ( x ) in gold nuclei for 0.001< x <0.1. For 0.01< x <0.1, this measurement tests the universality of the gluon distribution. macroscopic gluon fields. (again d-Au) 2.Characterization of correlated pion cross sections as a function of Q 2 (p T 2 ) to search for the onset of gluon saturation effects associated with macroscopic gluon fields. (again d-Au) transversely polarized protons resolve the origin of the large transverse spin asymmetries forward   production. (polarized pp) 3.Measurements with transversely polarized protons that are expected to resolve the origin of the large transverse spin asymmetries in reactions for forward   production. (polarized pp)  DOE milestone 

FMS for d-Au saturation physics p+p and d+Au    +   +X correlations with forward   hep-ex/ p+p in PYTHIAd+Au in HIJING Conventional shadowing will change yield, but not angular correlation. Saturation will change yield and modify the angular correlation. Sensitive down to x g ~ in pQCD scenario; few x in CGC scenario.

The Heavy Flavor Tracker The PXL: 2 layers of Si at mid rapidity Mid-rapidity Pointing Devices: IST + SSD The PXL is a new detector –30  m silicon pixels to yield 10  m space point resolution Direct Topological reconstruction of Charm –Detect charm decays with small c , including D 0  K  New physics –Charm collectivity and flow to test thermalization at RHIC –C & B Energy Loss to test pQCD in a hot and dense medium at RHIC The proposed Tracking Upgrades include –PXL (2 layers) –IST (2 layers) –SSD (existing layer) = PXL + IST + SSD

GEANT View of the Heavy Flavor Tracker

Charmed hadron Simulation Results Detector radii: TOF TPC (60 cm) SSD (23 cm) IST2 (17 cm) IST1 (12 cm) PXL2 (7.0 cm) PXL1 (2.5 cm) The Monte Carlo reconstructed yield of D 0 is very good –A complex p T dependence … however efficiency vs p T is the FOM –D 0 decay length is ~ 125  m –IST helps reduce search radius on HFT and thus reduces ghost track inefficiencies as well as allows more relaxed kinematic cuts on the data –Kinematic cuts in the software are a significant contributor to the total efficiency

Accessing Quark Helicities with W Bosons Maximal Party-Violation in Weak Interaction: Inherent spin sensitivity of W production Charge of the Boson provides flavor tagging: RHIC: 500 GeV CME in p+p collisions  the quark is usually a valence quark (large x)

Forward GEM Tracker (FGT) 6 triple-GEM disks covering 1 <  < 2  outer radius ~ 40 cm  inner radius varies with z position charge sign reconstruction probability of W above 80% for 30 GeV p T over the full acceptance of the EEMC for the full vertex spread ( > 90% out to η= 1.8) Probability to get the correct charge sign

GEM Prototypes meet Requirements 3 layers: 10x10cm GeV beam resolution x ~ 51 µm, y ~ 63 µm 32 GeV beam resolution x ~ 66 µm, y ~ 78 µm Efficiency plateau of ~ 90% (includes dead, noisy areas)  Detector electronics based on APV25S1 front-end chip (developed for CMS)  TechEtch foils  FNAL T963 (May 2-15, 2007)

Schedule Beam Use Request strongly coupled with detector upgrades to optimize the maximum physics output

References STAR Decadal Plan STAR (Tim Hallman) 2007 Annual DOE ReviewSTAR (Tim Hallman) 2007 Annual DOE Review The STAR Detector Upgrade Plan (Jim Thomas) 2007 RHIC&AGS Annual Users MeetingThe STAR Detector Upgrade Plan (Jim Thomas) 2007 RHIC&AGS Annual Users Meeting Overview of STAR Upgrades (Zhangbu Xu) 2006 RHIC&AGS Annual Users MeetingOverview of STAR Upgrades (Zhangbu Xu) 2006 RHIC&AGS Annual Users Meeting STAR Upgrade Plans and R&D (Richard Majka) STAR Beam Use Request (BUR2006) Forward Meson Spectrometer (FMS) Time-of-Flight Proposal DAQ1000 Heavy Flavor Tracker (HFT) Forward GEM Tracker (FGT) STAR Future Physics and Upgrade Planning (internal)